Susceptibility testing of yeasts to fluconazole by Etest and agar-diffusion disk test using the synthetic agar medium Mycoplate

A total of 50 clinical Candida isolates was tested against fluconazole using both the Etest and the agar-diffusion disk test on the synthetic agar medium Mycoplate. Inhibition zones were readable, although a residual yeast growth occurred within the inhibition zones. The diameter of the inhibition zones in the disk test correlated very well with the logarithmically transformed minimal inhibitory concentrations measured with the Etest. For an inhibition zone diameter equal to or greater than 22 mm, using a 25-mug disk, the isolates were considered as fluconazole-susceptible, and for zone diameters less than 22 mm, dose-dependent susceptibility (S-DD) or resistance to fluconazole was assumed. These results are in agreement with those of other authors. The Mycoplate medium appeared to be suitable for testing yeasts for their susceptibility to fluconazole.